textproduct: Rapid City

KEY MESSAGES

- Mild with gusty west/southwest winds through Saturday morning, then gusty northwest winds behind an arctic cold front later Saturday into Sunday accompanied by some light precipitation - Wind chills 0 to -25F by Sunday morning - Temperatures bounce back next week, but with low confidence given CWA proximity to arctic boundary

DISCUSSION

(This Evening Through Friday) Issued at 206 PM MST Fri Dec 26 2025

21z surface analysis had low pressure entering north central MT with a warm front into northeast NE. 50s/mid 60s behind it with 40s ahead of it over the CWA. Decent pressure falls over MT/WY supporting gusty southwest winds again, extending into the Black Hills/higher foothills. Water vapour loop had upper trough over southwest Canada/northwest CONUS, which will be our near-term forecast concern.

Today/Saturday morning, upper trough moves into the northern Rockies with embedded shortwave strengthening over the MT/ND/Canadian border. Mild weather will continue with gusty west/southwest winds at times. Temperatures will be above guidance in the west and near for the east.

Saturday afternoon through Sunday, embedded shortwave morphs into upper low as it moves into the Great Lakes. Surface low develops over MT and then zips into the central Plains as it deepens. The low will drag an arctic cold front through the CWA with moderate isallobaric forcing (3-5mb/hr pressure rises) Saturday night along with a narrow band of post-frontal frontogenetic forcing/moisture. Should see a band of light snow (perhaps briefly starting as light rain) zip through the CWA with gusty northwest winds. Latest guidance suggests the most likely outcome will be a high-end wind advisory from K2WX-KRAP given forecast soundings and squeeze zone. Probabilistic guidance at odds with regard gust potential. HREF chance >50mph gusts very low, but NBM paints 40-70% chance 45-55mph gusts, which is more in line with traditional MOS guidance, also matching subjective pattern recognition. Given discrepancies, will hold off on any headlines with main event starting after 28/00z. Other impact will be plummeting apparent temperatures, some 40-60 degrees colder than Saturday afternoon as wind chills drop to 0 to -25F by Sunday morning. Time to throw on your favorite winter weather gear. Temperatures will be near guidance/10-20F below normal.

Northwest flow aloft is expected for most of next week with a series of weak disturbances pushing/pulling the arctic boundary in/near the CWA with increasing forecast temperature spreads. Low confidence temperature forecast, but overall, slightly above in the southwest and probably colder than normal in the northeast.

AVIATION

(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 351 PM MST Fri Dec 26 2025

VFR conditions will persist through the forecast period. Breezy west to southwest winds will continue across portions of northeastern WY into the Black Hills with gusts of 30-35 kt.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.